THE GROWTH START ON THE HETEROVALENT GAAS-ZNSE INTERFACE UNDER TE, SEAND ZN TERMINATION

To improve the properties of ZnSe related devices grown on GaAs substr ates or ZnSe/GaAs heterostructures a deeper understanding of the II-VI /III-V interface is necessary. In particular island growth within the first few monolayers will influence the properties of such devices dra stically. Because theory predicts an enhanced stability for a special interface layer composition (Kley and Neugebauer, Phys, Rev, B 50 (199 3) 8616 [1]), we have varied the starting growth conditions by utilizi ng Zn, Se or Te termination of the GaAs (100) surface with different c overages. Only the layers grown on Te/GaAs which has a coverage of app roximately half a monolayer (ML) Te showed a two dimensional (2D) grow th start, pseudomorphic growth up to 400 nm, good crystal quality and reproducible electrical behavior. From all this we can conclude that a n initial layer with the theoretically proposed coverage should allow growth to remain in the 2D mode and thus result in an improved crystal quality. Further we have shown that it is possible to double the thic kness of pseudomorphic layers compared to values reported by other gro ups using conventional MBE.